4
Procedure for installing the thru-hull mount transducer
1. With the boat hauled out of the water, mark the location selected for mounting the
transducer on the bottom of the hull.
2. If the hull is not level within 15° in any direction, fairing blocks made out of teak should
be used between the transducer and hull, both inside and outside, to keep the
transducer face parallel with the water line. Fabricate the fairing block as shown below
and make the entire surface as smooth as possible to provide an undisturbed flow of
water around the transducer.
The fairing block should be smaller than the transducer itself to provide a channel to
divert turbulent water around the sides of the transducer rather than over its face.
BOW
Hole for
stuffing tube
Upper
half
Lower
half
Saw along slope of hull.
Figure 1-6 Construction of fairing block
3. Drill a hole just large enough to pass the threaded stuffing tube of the transducer
through the hull, making sure it is drilled vertically.
4. Apply a sufficient amount of high quality caulking compound to the top surface of the
transducer, around the threads of the stuffing tube and inside the mounting hole (and
fairing blocks if used) to ensure watertight mounting.
5. Mount the transducer and fairing blocks and tighten the locking nuts. Be sure that the
transducer is properly oriented and its working face is parallel to the water line.
Note: Do not over-stress the stuffing tube and locking nuts through excessive tightening,
since the wood block will swell when the boat is placed in the water. It is suggested
that the nut be tightened lightly at installation and retightened several days after the
boat has been launched.